Mercury safety switch for vehicles



Nov. 11, 1969 E, H. osTEEN MERCURY SAFETY SWITCH, FOR VEHICLES Filed Oct. 23, 1968 FIG 2 IIIIIAII IIIIIII Il FIG. I

BY W1 u' l y l ATTORNEY 3,478,183 MERCURY SAFETY SWITCH FORVVEHICLES Emmett H. Osteen, 700 E. Parmenter,

Lamar, Colo. 81052 Filed Oct. 23, 1968, Ser. No. 769,864 Int. Cl. H01h'35/02, 35/14 U.S. Cl. 20061.47 6 Claims ABSTRACT OF THE DISCLOSURE PRIOR ART Porter 2,417,993; Moore 2,744,175; English et al. 3,034,097.

OBJECTS The primary object of this invention is to provide a mercury switch adapted for use in the main electrical circuit of a vehicle so as to open the circuit in event of heavy impact, either from the front or rear, abnormal inclination upwardly or downwardly, or rolling-over of the vehicle. Such switches, broadly, have been used for many years, 'but in most instances the prior art switches automatically reset or, if they require resetting, they entail orientation of the switch casing in order to manipulate the mercury back into contact-making position. Those switches which automatically reset can cause fire after the impact occurs or if the vehicle rolls over and lands on its wheels, and the forced-reset type require either removal from the vehicle or a special pivot mounting for manipulation. The object now is to provide a non-automatic reset type mercury switch which can be lixedly mounted on a vehicle and which can be easily reset by a push button.

These and other objects will be apparent from the following specification and drawing, in which:

FIG. l is a side elevation;

FIG. 2 is a plan view; and,

FIG. 3 is an end view of the switch.

Referring now to the drawing, in which like reference numerals denote similar elements, the mercury switch 2 is composed of a hollow oblong casing 4 made of insulating material, such as one of the well known plastics, and having a top wall 6, bottom walli'S, front wall 10, rear wall 12, and end walls 14 and 16. Suitable conventional mounting means, such as lugs 17 are provided so that the switch may be fixedly mounted at some convenient location on a vehicle.

Extending forwardly from front wall are two terminal posts 18, for connecting the switch in series with the circuit to be protected, such as the main4 circuit leading from a vehicle battery. Electrically connected to the terminal posts 18 and 20 are two spaced electrodes 22, 24 (they may be integral with terminal posts 18, 20) of generally pyramid shape in transverse cross section. Suitable seals, not shown, may be provided to assure a fluid-tight fitting of the electrodes through front wall 10.

As will be apparent from FIGS. 1 and 2, the bottoms 23 of electrodes 22, 24 fit against the bottom wall 8 of casing 4, and their outwardly-inclined inner sides 25a, 25b, together with the central part of bottom wall 8, define a trough 26 in which a pool of mercury 28 is nor- United States Patent() 3,478,183 Patented Nov. Il, 1969 ice mally confined. Between the inwardly inclined outer sides 40a, 40b of the electrodes and plungers 34, 36, described below, are pockets 30, 32, either of which can accommodate the pool of mercury in event it is dislodged from the trough 26. p A

Normally engaged against the inner sides of end walls 14, 16 and slidably fitting within casing 4 so as to seal against the top, bottom and sides thereof are plungers 34, 36 each having a beveled inner edge 38a, 38b at the bottom 4which is generally complementary with the opposite outer side of the electrode for engaging against the outer side 40a, 40b. Plungers 34, 36 are pushed inwardly by reset buttons 42, 44 respectively, which Vslide through bearing collars 46, 48, and which are biased outwardly to the position shown in FIGS. 1 and 2 by springs 50. The push buttons are covered by thin, exible rubber cups 52, 54. If casing 4 is not formed of transparent material, a window 56 is preferably provided in the front wall, although it could be in the rear or top wall, so that the condition of the switch canY be ascertained by inspection. v

In normal operation, the mercury 28 is conned in trough 26 so as to establish an electrical circuit between electrodes 22, 24. However, upon impact from front or rear, or upon extreme upward or downward tipping or sidewise tilting of the vehicle, the mercury will be dislodged -from trough 26 and trapped in one or the other or` both of pockets 30, 32. Also, if the vehicle rolls over, and even if it lands on its wheels, enough mercury will be dislodged from trough 26 and trapped in pockets 30, 32 so as to open the electrical circuit between the electrodes.

For resetting the switch, one or ythe other, or both, of plungers 34, 36 is pushed in by a reset button 42 or 44 so as to squeeze the mercury between the beveled edge 38a or 38b of a plunger and the inwardly inclined side 40a or 40b of an electrode thereby -forcing the mercury up over the top of an electrode and back into trough 26.

I claim:

1. A mercury switch, comprising a hollow casing formed of insulating material having top, bottom, side and end walls,

a spaced pair of electrically conductive electrodes disposed adjacent the inner side of the bottom wall and defining between opposite inner sides thereof a trough,

said electrodes being spaced from the end vwalls of the casing,

electrical terminal means connecting said electrodes to the exterior of said casing,

mercury normally forming a pool in said trough and normally establishing an electrical circuitbetween `said electrodes, i' 'l a pair of pusher means movably disposed in said casing each rbetween an electrode and an end wall of the casing and being movable towards and away from the electrodes,

said pusher means and opposite outer sides of said electrodes defining pockets for receiving mercury dislodged -from said trough,

and manually operable means on the exterior.. of said casing for forcing said pusher towards the outer sides of said electrodes for forcing mercury from said pockets back into said trough.

2. A mercury switch as claimed in claim -1, said electrodes being of substantially pyramid-shape in cross-section and extending across said casing from the front wall to the rear wall thereof.

3. The combination claimed in claim 2, said pusher means having lower portions facing said electrodes which are substantially 4complementary with the sides of the electrodes which they face'.

Y v 3 4v Th? Somblti@ Claimed inlaim 1,111@ means@ Y A References Cited towards the outer sides of said electrodes comprising a pair of push buttons each aixed to a plunger and extend- 1,858,191 5/1932 Hadley et al- ZOO-6147 ing.through an end wall of the casing to the exterior 5 3,354,283 11/1967 Flynn 20o-61'47 XR thereof. y `5. The combination claimed in claim 4, and means for ROBERT K' SCHAEFER Primary Exammer vbiasing said push buttons outwardly. M. GINSBURG, Assistant Examiner .i 6;-The..combination claimed in claim 1, said pusher meanscomprising plungers slidably sealing against the lo U.S. C1. X.R.

inner sides of said casing. 200--152 

